1. Field of the Invention
The invention is directed to a projecting apparatus, and more particularly, to a projecting apparatus having favorable heat dissipation efficiency.
2. Description of Related Art
A projecting apparatus is a display apparatus configured to create a large-sized screen. An imaging principle of the projecting apparatus is to convert an illumination beam generated by a light source into an image beam by using a light valve, and then to project the image beam onto a screen or a wall surface via a projection lens so as to form an image.
FIG. 1 shows a configuration of devices in a conventional projecting apparatus. Referring to FIG. 1, a projecting apparatus 100 includes a chassis 120, a plurality of light source heat sinks 140a, 140b, 140c, a first fan set 160, a second fan set 180 and a power supply 190. The chassis 120 has two air inlets 120a, 120b, and a plurality of air outlets 120c, 120d, 120e. The first fan set 160 is disposed at a first air inlet 120a, and the second fan set 180 is disposed at a second air inlet 120b. 
When the first fan set 160 and the second fan set 180 respectively drive air to enter the chassis 120 via the first air inlet 120a and the second air inlet 120b, the air forms air flows having the rotational property after passing through the fan sets 160 and 180. Next, the two air flows having the rotational property pass through the projecting apparatus 100, converge in front of the air outlets 120c and 120d to cause a turbulence, thereby forming a flow resistance. Consequently, the two air flows are hindered, the air flow rate decreases and noise increases. In addition, a flow direction of the air flow having the rotational property is hard to control. Hence an additional air guiding design is required in order to prevent a non-uniform distribution of air flow that leads to low heat dissipation efficiency of the projecting apparatus 100.
Furthermore, after the first fan set 160 sucks cold air from outside into the projecting apparatus 100, the light source heat sink 140a and the light source heat sink 140b are cooled in sequence. Next, the power supply 190 is cooled by hot air. Finally, the hot air is discharged via the air outlets 120c and 120d. Since the cold air is heated after cooling the light source heat sinks 140a and 140b, it provides a limited cooling effect to the power supply 190 downstream.
Following the above, in the configuration of devices in the conventional projecting apparatus 100, the positions of the fan sets 160, 180, the air inlets 120a, 120b and the air outlets 120c, 120d affect the flow directions of the air flows sucked into the projecting apparatus 100. In addition, the positions of each of the heat sinks 140a, 140b, 140c and the power supply 190 in the projecting apparatus 100 also affect the heat dissipation efficiency. Therefore, the influence of relative positions of each element in the projecting apparatus on the heat dissipation efficiency is a topic worthy of discussion.
U.S. patent publication no. 2011/0157560 discloses a projector including two air inlets disposed on the same side surface and two air outlets disposed on opposite side surfaces, wherein one air passage is formed between one air inlet and one air outlet, and another air passage is formed between another air inlet and another air outlet. The two air passages are straight passages parallel to each other, so that the air flows generated do not interfere with each other. U.S. Pat. No. 6,739,831 discloses a cooling device for projector, wherein a first air inlet, a second air inlet, and two air outlets disposed on different sides are provided on a casing of the projector. The air outlets located on different sides of the casing are perpendicular to each other, but the casing further has air ducts for circulation of two air flows. Chinese patent publication no. 102289139 discloses a laser projector, wherein heat sink fins of a light source module are disposed between a heat sink fan and an air outlet.